| Employer | State | City | |
| S & T Plumbing | Texas | Irving | View Profile |
| S. P. McCarl & Company, Inc. | Pennsylvania | Altoona | View Profile |
| Sarracco Mechanical Services Inc. | Connecticut | Naugatuck | View Profile |
| Sepco Air | Florida | Sanford | View Profile |
| Sertec Industrial Inc. | Virginia | Alexandria | View Profile |
| Service Logic | Colorado | Denver | View Profile |
| Services Of America | Virginia | Alexandria | View Profile |
| Shapiro & Duncan, Inc. | Maryland | Rockville | View Profile |
| ShureLine Construction & ShureLine Electrical | Delaware | Smyrna | View Profile |
| ShureLine Construction & ShureLine Electrical | Delaware | Smyrna | View Profile |
| SITECH Inc. | Florida | Plant City | View Profile |
| Skill Supply | New Mexico | Albequerque | View Profile |
| Smart Air Systems, Inc. | Florida | Margate | View Profile |
| Sodexo USA | Maryland | Gaithersburg | View Profile |
| Spalding Gas | Georgia | Griffin | View Profile |
| Spears Refrigeration | Texas | Arlington | View Profile |
| Stan's Heating & Air Conditioning, Inc. | Texas | Austin | View Profile |
| Stanco Climate Control | New Jersey | Manalapan | View Profile |
| Standard Mechanical Systems | Texas | Houston | View Profile |
| Stantec | New York | New York | View Profile |
| Star Service, Inc. of Jackson | Mississippi | Byram | View Profile |
| Stulz Air Technology Systems, Inc. | Maryland | Frederick | View Profile |
| Sullivan Super Service | Pennsylvania | Braddock | View Profile |
| Sullivan Super Service | Pennsylvania | Braddock | View Profile |
| Swick Plumbing Heating and Air | Michigan | Marquette | View Profile |